Alloys



Patented Sept. 4, 1945 "UNITED. sT-A'flzs PATENT OFFICE ALLOYS Robert a. Leach, Fairfleld, com, assignor to Randy & Harman, New York, N. Y., a corpo:

ration of New York No Drawina.

Application September as, 1942, Serial No. 459,838

'-4 Claims. (Gus-11s) highly satisfactory for commercial purposes and have been sold in large quantities. The patented alloys flow freely at 1175 F. or less and have such malleability, ductility. and strength as to be readilyi fabricated into sheet and wire and to make strong joints. In those alloys, the silver content ranges from about 48 to- 52% and the preferred 20 commercial form contains about 50% of silver.

As a result of further investigation of the properties of the quaternary alloys of silver, copper, cadmium, and zinc, I have found that the optimum characteristics of such alloys can be obtained provided certain definite relationships among the several metals are maintained. If

those relationships are observed, the alloys will have the desired qualities of low flow point, malleability, ductility, and strength, and may contain a less amount of silver than that employed in the alloys of the patent above mentioned. ,With the recent increases in the price of silver, the reduction of the silver content without any considerable impairment of the desirable characteristics of the alloys is of considerable importance, particularlv to users engaged in manufacture on a large scale.

-.'In the new alloys, the silver content ranges from about 44% to about 47%% and the ratio of silver to copper varies between about 2.6 and about 3.5 and the ratio of zinc to cadmium varies between about 0.0 and about 1.2.

In my Reissue Patent No. 20,638, dated January 25, 1938, I stated that the presence of zinc or cadmium or both has a bearing on the melting point of quaternary alloys, in which they are preseat with silver and copper, and explained that, in general, the higher the proportions of zinc or cadmium or both, the lower the melting point. I also disclosed that it is not desirable to'employ an aggregate amount of zinc and cadmium in excess of about 40% and that, for most purposes. a less amount was to be preferred. In the new alloys,

to the zinc and cadmium content is followed and the total amount of zinc and cadmium is kept below about 40%.

' A specific example of the new alloys may have .5 the following approximate analysis:

Example N0. 1 I Per cent Silver v a 45.5 Copper 16.5 zinc-' 18. Cadmium 20.0

Alloys of the above,composition flow freely atapproximately 1160 F. and can be fabricated into sheet and wire. A reduction in the total amount of zinc and cadmium gi'ves greater malleability and ductility and the alloy flows freely at about the, same temperature as, before. Such an alloy may be of the following approximate analysis:

1 Example. No. 2 l Per cent Silver 475 Copper 15.8 Zinc 18.4 Ca 18.3

I In the alloys of. Examples Nos. land 2, the si1-' vet to copper ratios are, respectively, about 2.8

and 3 and the zinc to cadmium ratios are, respectively, 0.9 and 1. If the silver content and the aggregate amount of zinc and cadmium are kept within the limits above specified and the silvercopper ratio is increased to about 3.5 and the zinc-cadmium ratio increased to about 1.2, the

alloy will again'flow freely at temperatures of about 1150 F. to l 1". An example of such an alloyis of the following approximate analysis:

0 Example No.3

Per cent Silver I 47,5 Copper 13.5 Zinc 21.0 Cadmium 18.0

Alloys of the invention can be-used for general brazing and welding purposes and, since they flow freely at the relatively low temperatures of about 1150 F. to about 1160 it, they are applicable for so many purposes for which alloys of higher flow point cannot be used because of the liability of damase being done to the objects to be Joined on exposure to high tuapsratures. The new alloys have satisfactory physical characteristics, as

makes their use advantageous in operations in which cost is of major importance.

I claim:

1. An alloy which consists of silver ranging from about 44% to about 47 95. copp r in an amount such that the ratio of silver to copper varies between about 2.6 and about 3.5, and zinc and cadmium in an aggregate amount not exceeding about 40%, with the zinc to cadmium ratio varying from about 0.9 to about 1.2. 

